使用mingw编译websocketpp示例代码时，未定义对“std::errc::operation_canceled

Question

我正在尝试使用websocketpp编写一个使用websocket进行通信的跨平台程序。我想使用基于asio的传输层。

我的理解是，如果我使用C++11，我可以将asio配置为独立于boost并使用std::thread，并且只有在这种情况下，websocketpp才是类似的头。

然而，当我实际尝试以这种方式编译任何websocketpp教程时，例如tutorials/utility_client，它在g++和clang上运行良好，但我在mingw:上遇到了奇怪的编译错误

In file included from websocketpp-0.6.0/include/websocketpp/config/asio_no_tls_client.hpp:32:0,
                 from main.cpp:7:
websocketpp-0.6.0/include/websocketpp/transport/asio/endpoint.hpp: In member function ‘void websocketpp::transport::asio::endpoint<config>::handle_accept(websocketpp::transport::accept_handler, const error_code&)’:
websocketpp-0.6.0/include/websocketpp/transport/asio/endpoint.hpp:764:28: error: ‘operation_canceled’ is not a member of ‘std::errc’
             if (asio_ec == lib::asio::errc::operation_canceled) {
                            ^

我不明白这意味着什么以及如何解决这个问题。这似乎与缺乏助推无关——根据这个并不总是准确的网站，std::errc::operation_canceled似乎是一个定义明确的C++11符号。这是否意味着我的工具链坏了/有缺陷？我试着安装了一个不同版本的mingw工具链，但它也出现了同样的问题。

我找不到任何引用任何有类似问题的人，因为找不到这个符号，所以也许我配置的库有错？这是我的汇编行：

"$CXX" -std=c++11 -Iasio-1.10.6/include -Iwebsocketpp-0.6.0/include -D_WEBSOCKETPP_CPP11_THREAD_=1 -DASIO_STANDALONE=1 main.cpp -lpthread

我制作了一个存储库来帮助复制我的确切设置，但这里没有太多内容——我从它们各自的repo中下载了最新版本的两个libs。由于编译在其中一个include中终止，main.cpp的主体似乎并不太相关，但我只是在使用他们的教程代码。

如果有人能给我一句话，我将不胜感激

编辑：我真的不确定，但我已经报告了这是mingw-w64的一个错误：http://sourceforge.net/p/mingw-w64/support-requests/105/

Answer 1

我已经将此报告为mingw-w64 的错误

mingw-w64编译器在没有定义该错误代码方面是C++11不兼容的，但人们已经知道了，这是经过深思熟虑的。（尽管我没有知道他们为什么不能修复它。）

相关头文件为：

<toochain_dir>/mingw64/x86_64-w64-mingw32/include/c++/x86_64-w64-mingw32/bits/error_constants.h

这是enum class std::errc的定义：

// Most of the commented-out error codes are socket-related and could be
// replaced by Winsock WSA-prefixed equivalents.
  enum class errc
    {
//    address_family_not_supported =        EAFNOSUPPORT,
//    address_in_use =              EADDRINUSE,
//    address_not_available =           EADDRNOTAVAIL,
//    already_connected =           EISCONN,
      argument_list_too_long =          E2BIG,
      argument_out_of_domain =          EDOM,
      bad_address =                 EFAULT,
      bad_file_descriptor =             EBADF,
//    bad_message =                 EBADMSG,
      broken_pipe =                 EPIPE,
//    connection_aborted =          ECONNABORTED,
//    connection_already_in_progress =      EALREADY,
//    connection_refused =          ECONNREFUSED,
//    connection_reset =            ECONNRESET,
//    cross_device_link =           EXDEV,
//    destination_address_required =        EDESTADDRREQ,
      device_or_resource_busy =         EBUSY,
      directory_not_empty =             ENOTEMPTY,
      executable_format_error =         ENOEXEC,
      file_exists =                     EEXIST,
      file_too_large =              EFBIG,
      filename_too_long =           ENAMETOOLONG,
      function_not_supported =          ENOSYS,
//    host_unreachable =            EHOSTUNREACH,
//    identifier_removed =          EIDRM,
      illegal_byte_sequence =           EILSEQ,
      inappropriate_io_control_operation =  ENOTTY,
      interrupted =                 EINTR,
      invalid_argument =            EINVAL,
      invalid_seek =                ESPIPE,
      io_error =                EIO,
      is_a_directory =              EISDIR,
//    message_size =                EMSGSIZE,
//    network_down =                ENETDOWN,
//    network_reset =               ENETRESET,
//    network_unreachable =             ENETUNREACH,
//    no_buffer_space =             ENOBUFS,
#ifdef _GLIBCXX_HAVE_ECHILD
      no_child_process =            ECHILD,
#endif
//    no_link =                 ENOLINK,
      no_lock_available =           ENOLCK,
//    no_message_available =            ENODATA,
//    no_message =              ENOMSG,
//    no_protocol_option =          ENOPROTOOPT,
#ifdef _GLIBCXX_HAVE_ENOSPC
      no_space_on_device =          ENOSPC,
#endif
//    no_stream_resources =             ENOSR,
      no_such_device_or_address =       ENXIO,
      no_such_device =              ENODEV,
      no_such_file_or_directory =       ENOENT,
      no_such_process =             ESRCH,
      not_a_directory =             ENOTDIR,
//    not_a_socket =                ENOTSOCK,
//    not_a_stream =                ENOSTR,
//    not_connected =               ENOTCONN,
      not_enough_memory =           ENOMEM,
#ifdef _GLIBCXX_HAVE_ENOTSUP
      not_supported =               ENOTSUP,
#endif
//    operation_canceled =          ECANCELED,
//    operation_in_progress =           EINPROGRESS,
#ifdef _GLIBCXX_HAVE_EPERM
      operation_not_permitted =         EPERM,
#endif
//    operation_not_supported =         EOPNOTSUPP,
#ifdef _GLIBCXX_HAVE_EWOULDBLOCK
      operation_would_block =           EWOULDBLOCK,
#endif
//    owner_dead =              EOWNERDEAD,
      permission_denied =           EACCES,
//    protocol_error =              EPROTO,
//    protocol_not_supported =          EPROTONOSUPPORT,
      read_only_file_system =           EROFS,
      resource_deadlock_would_occur =       EDEADLK,
      resource_unavailable_try_again =      EAGAIN,
      result_out_of_range =             ERANGE,
//    state_not_recoverable =           ENOTRECOVERABLE,
//    stream_timeout =              ETIME,
//    text_file_busy =              ETXTBSY,
#ifdef _GLIBCXX_HAVE_ETIMEDOUT
      timed_out =               ETIMEDOUT,
#endif
      too_many_files_open_in_system =       ENFILE,
      too_many_files_open =             EMFILE,
      too_many_links =              EMLINK
//    too_many_symbolic_link_levels =       ELOOP,
#ifdef _GLIBCXX_HAVE_EOVERFLOW
    ,
      value_too_large =             EOVERFLOW
#endif
//    wrong_protocol_type =             EPROTOTYPE
   };

您可以看到operation_canceled就是其中之一。

正如建议的那样，您需要使用winsock错误代码WSAECANCELLED，在CCD_ 13中定义。如果你想要便携性，你当然需要以主机OS的编译时间确定为条件来使用CCD_ 14。